全文获取类型
收费全文 | 1264篇 |
免费 | 34篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 262篇 |
金属工艺 | 37篇 |
机械仪表 | 37篇 |
建筑科学 | 26篇 |
矿业工程 | 2篇 |
能源动力 | 63篇 |
轻工业 | 66篇 |
水利工程 | 13篇 |
石油天然气 | 6篇 |
无线电 | 137篇 |
一般工业技术 | 274篇 |
冶金工业 | 178篇 |
原子能技术 | 2篇 |
自动化技术 | 179篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 20篇 |
2020年 | 15篇 |
2019年 | 18篇 |
2018年 | 40篇 |
2017年 | 40篇 |
2016年 | 36篇 |
2015年 | 12篇 |
2014年 | 34篇 |
2013年 | 70篇 |
2012年 | 42篇 |
2011年 | 62篇 |
2010年 | 52篇 |
2009年 | 62篇 |
2008年 | 66篇 |
2007年 | 54篇 |
2006年 | 35篇 |
2005年 | 42篇 |
2004年 | 26篇 |
2003年 | 37篇 |
2002年 | 38篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 21篇 |
1998年 | 35篇 |
1997年 | 25篇 |
1996年 | 36篇 |
1995年 | 27篇 |
1994年 | 21篇 |
1993年 | 21篇 |
1992年 | 20篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 19篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 20篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 17篇 |
1976年 | 14篇 |
1974年 | 5篇 |
1973年 | 7篇 |
排序方式: 共有1298条查询结果,搜索用时 0 毫秒
71.
Ashley T. Buckle L. Datta S. Emeny M.T. Hayes D.G. Hilton K.P. Jefferies R. Martin T. Phillips T.J. Wallis D.J. Wilding P.J. Chau R. 《Electronics letters》2007,43(14)
The heterogeneous integration of InSb quantum well transistors onto silicon substrates is investigated for the first time. 85 nm gate length FETs with fT = 305 GHz at Vds = 0.5 V and DC performance suitable for digital logic are demonstrated on material with a buffer just 1.8 mum thick. An initial step towards integrating InSb FETs with mainstream Si CMOS for high-speed energy-efficient logic applications has been achieved. 相似文献
72.
Virus Matryoshka: A Bacteriophage Particle—Guided Molecular Assembly Approach to a Monodisperse Model of the Immature Human Immunodeficiency Virus 下载免费PDF全文
Pooja Saxena Li He Andrey Malyutin Siddhartha A. K. Datta Alan Rein Kevin M. Bond Martin F. Jarrold Alessandro Spilotros Dmitri Svergun Trevor Douglas Bogdan Dragnea 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(42):5862-5872
Immature human immunodeficiency virus type 1 (HIV‐1) is approximately spherical, but is constructed from a hexagonal lattice of the Gag protein. As a hexagonal lattice is necessarily flat, the local symmetry cannot be maintained throughout the structure. This geometrical frustration presumably results in bending stress. In natural particles, the stress is relieved by incorporation of packing defects, but the magnitude of this stress and its significance for the particles is not known. In order to control this stress, we have now assembled the Gag protein on a quasi‐spherical template derived from bacteriophage P22. This template is monodisperse in size and electron‐transparent, enabling the use of cryo‐electron microscopy in structural studies. These templated assemblies are far less polydisperse than any previously described virus‐like particles (and, while constructed according to the same lattice as natural particles, contain almost no packing defects). This system gives us the ability to study the relationship between packing defects, curvature and elastic energy, and thermodynamic stability. As Gag is bound to the P22 template by single‐stranded DNA, treatment of the particles with DNase enabled us to determine the intrinsic radius of curvature of a Gag lattice, unconstrained by DNA or a template. We found that this intrinsic radius is far larger than that of a virion or P22‐templated particle. We conclude that Gag is under elastic strain in a particle; this has important implications for the kinetics of shell growth, the stability of the shell, and the type of defects it will assume as it grows. 相似文献
73.
Optimization of bead geometry of submerged arc weld using fuzzy based desirability function approach
Ankita Singh Saurav Datta Siba Sankar Mahapatra Tapan Singha Gautam Majumdar 《Journal of Intelligent Manufacturing》2013,24(1):35-44
The present study highlights application of Taguchi’s robust design coupled with fuzzy based desirability function approach for optimizing multiple bead geometry parameters of submerged arc weldment. Fuzzy inference system has been adapted to avoid uncertainly, imprecision and vagueness in experimentation as well as in data analysis by traditional Taguchi based optimization approach. Detailed methodology and unique features of the proposed method has been highlighted through a case study. The said approach can efficiently be used in off-line quality control of any production process as well as automation of the process. 相似文献
74.
Following the assertion of Westwater, on the consideration of the radiometer operating frequency around 22GHz for remote sensing of water vapour distribution in the atmosphere, a comprehensive study has been made to re-examine the validity of considering frequency away from resonant frequency for both dry locations, like Antarctica and for tropical region, Calcutta. Radiosonde data have been utilized to calculate line shape functions and weightingfunctions at different operating frequencies. Results indicate that water vapour sensitive 22·235 GHz is still better for dry climatic regions like Antarctica, whereas, for wet air locations, choice of frequency will be different from the resonance peak. 相似文献
75.
A Measurement‐Based Approach for Designing Fixed‐Order Controllers for Unknown Closed‐Loop Architecture 下载免费PDF全文
Sofiane Khadraoui Hazem N. Nounou Mohamed N. Nounou Aniruddha Datta Shankar P. Bhattacharyya 《Asian journal of control》2016,18(2):686-698
This paper presents a new technique to design fixed‐structure controllers for linear unknown systems using a set of measurements. In model‐based approaches, the measured data are used to identify a model of the plant for which a suitable controller can be designed. Due to the fact that real processes cannot be described perfectly by mathematical models, designing controllers using such models to guarantee some desired closed‐loop performance is a challenging task. Hence, a possible alternative to model‐based methods is to directly utilize the measured data in the design process. We propose an approach to designing structured controllers using a set of closed‐loop frequency‐domain data. The principle of such an approach is based on computing the parameters of a fixed‐order controller for which the closed‐loop frequency response fits a desired frequency response that describes some desired performance indices. This problem is formulated as an error minimization problem, which can be solved to find suitable values of the controller parameters. The main feature of the proposed control methodology is that it can be applied to stable and unstable plants. Additionally, the design process depends on a pre‐selected controller structure, which allows for the selection of low‐order controllers. An application of the proposed method to a DC servomotor system is presented to experimentally validate and demonstrate its efficacy. 相似文献
76.
The effect of 1-cyclohexylthio-2-mercaptobenzimidazole (CMB) on the vulcanization of NR accelerated by N-oxydiethylene thiocarbamyl-N′-oxydiethylene sulfenamide (OTOS) has been studied. It is found that CMB delays the onset of cure and generates 2-mercaptobenzimidazole during vulcanization. The results indicate the retarding as well as antioxidant activity of CMB. 相似文献
77.
Management Issues of a Mobile Agent-Based Service Environment 总被引:1,自引:0,他引:1
This paper introduces the concepts of a servicemanagement system for mobile agent-based services. Incontrast to several other approaches in whichagent-based applications are used to handletraditional network or service managementaspects, this paper describes a way to manage thedistributed agent environment itself. The proposedapproach was designed and developed by using OSI SystemsManagement concepts as a starting point, which are modified andadjusted in order to fulfill the new requirementsassociated with the mobile agent paradigm. However, thispaper does not cover integration or co-existence of the introduced agent management system (AMS)and traditional OSI management systems. Instead, theentire AMS environment is based on mobile agenttechnology. At present, this approach is validated inthe context of the European research project MobileAgent Environments in Intelligent Networks(MARINE). 相似文献
78.
Datta S Forrest SR Volodin B Ban VS 《Journal of the Optical Society of America. A, Optics, image science, and vision》2005,22(8):1624-1629
We describe a wavelength multiplexer design that employs multiple transmission volume Bragg gratings written in the same region of a photosensitive glass having a through channel loss of < 0.5 dB. A two-channel multiplexer for wavelengths of lambda = 1310 and 1550 nm is demonstrated to test our design methods and assumptions. Agreement between simulation and experiment is within 0.2 dB at the peak diffraction efficiency. Grating apodization is used to reduce the interchannel cross talk from (13.5 +/- 0.5) to (41.5 +/- 8.5) dB, with an experimental through channel loss of (0.6 +/- 0.2) dB. Effects of angular dispersion on diffraction efficiency and grating spectral shape due to the finite diameter of the incident reading beam are also analyzed. 相似文献
79.
RSS (really simple syndication) based feeds have become the defacto mechanism of web based publish subscribe. Peer-to-Peer
delivery of such feeds can not only alleviate the load at the content server, but also reduce the dissemination latency. However,
due to openness of P2P system, malicious peers can join the network as easily as normal peers do. Such malicious peers may
pretend to relay but actually not, and thus deny service, or even disseminate counterfeit updates, rendering a Peer-to-Peer
mechanism not only useless, but even harmful (e.g. by false updates). We propose overlay independent randomized strategies
to mitigate these ill-effects of malicious peers at a marginal overhead, thus enjoying the benefits of Peer-to-Peer dissemination,
along with the assurance of content integrity in RSS like web-based publish-subscribe applications without altering currently
deployed server infrastructure. We conduct analysis of performance of our proposal by modeling behavior of the system and
validating the same with simulation. Results show that our proposal is effective, robust and scalable. 相似文献
80.
Benchmarking nanotechnology for high-performance and low-power logic transistor applications 总被引:1,自引:0,他引:1
Chau R. Datta S. Doczy M. Doyle B. Jin B. Kavalieros J. Majumdar A. Metz M. Radosavljevic M. 《Nanotechnology, IEEE Transactions on》2005,4(2):153-158
Recently there has been tremendous progress made in the research of novel nanotechnology for future nanoelectronic applications. In particular, several emerging nanoelectronic devices such as carbon-nanotube field-effect transistors (FETs), Si nanowire FETs, and planar III-V compound semiconductor (e.g., InSb, InAs) FETs, all hold promise as potential device candidates to be integrated onto the silicon platform for enhancing circuit functionality and also for extending Moore's Law. For high-performance and low-power logic transistor applications, it is important that these research devices are frequently benchmarked against the existing Si logic transistor data in order to gauge the progress of research. In this paper, we use four key device metrics to compare these emerging nanoelectronic devices to the state-of-the-art planar and nonplanar Si logic transistors. These four metrics include: 1) CV/I or intrinsic gate delay versus physical gate length L/sub g/; 2) energy-delay product versus L/sub g/; 3) subthreshold slope versus L/sub g/; and 4) CV/I versus on-to-off-state current ratio I/sub ON//I/sub OFF/. The results of this benchmarking exercise indicate that while these novel nanoelectronic devices show promise and opportunities for future logic applications, there still remain shortcomings in the device characteristics and electrostatics that need to be overcome. We believe that benchmarking is a key element in accelerating the progress of nanotechnology research for logic transistor applications. 相似文献